A major outbreak of severe weather (SPC storm reports) occurred across much of the southern Great Plains region of the US on 24 May 2011. One of the ingredients for this severe weather scenario was the approach of a strong jet stream, which was rounding the base of a broad upper level trough located over the Rocky Mountains. Due to these strong winds, a prominent mountain wave signature was seen on AWIPS images of 4-km resolution GOES-13 6.5 Âµm and 1-km resolution MODIS 6.7 Âµm “water vapor channel” data (above). Overlays of the RUC80 model isotachs at the 500 hPa, 400 hPa, 300 hPa, 250 hPa, and Maximum Wind levels showed the magnitude of these jet stream winds.

Strong winds were also found at the surface, and McIDAS images of GOES-13 0.63 Âµm visible channel data (below; click image to play animation) showed several large plumes of blowing dust (along with some smoke plumes from a few wildfires) which streamed eastward and northeastward behind the dryline that acted as the focus for the development of the severe thunderstorms. The haziness seen across the southeastern half of Texas was due to smoke which had been transported northward from fires burning in the Yucatan Peninsula region of Mexico.

GOES-13 sounder Total Precipitable Water (TPW) derived product images (below) revealed that TPW values in excess of 30 mm or 1.2 inches (yellow color enhancement) began to stream northward from Texas into Oklahoma by 18:00 UTC. This moisture helped to fuel the development and maintenance of the deep convection across the region.

GOES-13 sounder Total Precipitable Water derived product images

The 12 UTC rawinsonde report from Norman, Oklahoma revealed a classic “loaded gun” type of profile, which would lead to a very unstable airmass once strong surface heating took place during the morning and early afternoon hours. GOES-13 sounder Lifted Index (LI) derived product images (below) showed LI values of -10 to -13 C (red to violet color enhancement) just ahead of the dryline, where the atmosphere had indeed become very unstable.

GOES-13 sounder Lifted Index derived product images

Once the severe thunderstorms began to form across western Oklahoma after 18:15 UTC, GOES-13 6.5 Âµm water vapor channel images (below) displayed a pronounced warm/dry signature (orange color enhancement) immediately behind the storms — this could be the signature of a strong and large-scale rear flank downdraft in the wake of the storms.

A 250-meter resolution MODIS true color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (above; viewed using Google Earth) revealed one of the 24 May tornado damage tracks (oriented from southwest to northeast) which was located just to the northwest of Oklahoma City. Early in its life cycle, the tornado crossed Interstate 40, overturning a number of vehicles.

A comparison of before (22 May 2011) and after (26 May 2011) MODIS true color images (below) showed that the tornado damage path was not present on the 22 May image,

MODIS true color Red/Green/Blue (RGB) images before (22 May) and after (26 May) the 24 May tornado even

McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation; also available as a QuickTime movie) showed the rapid development of the supercell thunderstorm that produced the deadly tornado that struck Joplin, Missouri (station identifier JLN) on 22 May 2011. The GOES-13 satellite had been placed into Rapid Scan Operations (RSO), providing images as frequently as every 5-10 minutes. Very distinct overshooting tops could be seen with this large thunderstorm as it developed in extreme southeastern Kansas and moved eastward ahead of an advancing cold frontal boundary. According to the National Weather Service Springfield MO damage survey, the Joplin tornado produced EF-5 damage with a path width of 3/4 mile and a path length of 6 miles, and was responsible for 132 deaths and 750 injuries.

A 250-meter resolution MODIS true color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below; displayed using Google Earth) showed the line of thunderstorms developing from western Missouri into extreme southeastern Kansas.

A comparison of AWIPS images of the GOES-13 10.7 Âµm IR channel data at 21:25 UTC with overlays of the corresponding Automated Thermal Couplet Detection product and the past hour of SPC storm reports (below) revealed a strong thermal couplet of 12.7Âº C at that time (about 1 hour and 16 minutes before the Joplin tornado) — note that the location of the thermal couplet indicator is parallax-corrected, moving it just to the southeast of where the cold/warm thermal couplet is seen on the non-parallax-corrected GOES-13 IR image. This particular thermal couplet was associated with a west-to-east swath of hail as large as 1.75 inch in diameter that began in far southeastern Kansas at 21:02 UTC, along with a report of wind gusts to 62 mph. The Joplin tornado began to move into the city around 22:41 UTC (5:41 pm local time).

GOES-13 IR image + Thermal Couplet product + SPC storm reports

The Overshooting Tops detection and Thermal Couplet detection products are collaborative efforts between researchers at the NASA Langley Research Center and CIMSS. The development, generation, and evaluation of these products are part of the GOES-R Proving Ground effort; these products will be operational with data from the ABI instrument on GOES-R.

Meteosat-9 visible channel images (above) showed the volcanic eruption cloud emanating from the GrÃ­msvÃ¶tn volcano in Iceland on 21 May 2011(images courtesy of Dave Santek, SSEC). According to the Icelandic Met Office, at 21:00 UTC the eruption plume had risen to an altitude of over 65,000 ft (~20 km). It is interesting to note that the London VAAC reported

EXTREME LIGHTNING ACTIVITY DETECTED BY ATDNET SYSTEM OF UK METOFFICE, 7000 BETWEEN 1900Z AND 0100Z

The volcanic eruption cloud was even apparent on the very edge of GOES-13 (GOES-East) imagery, as can be seen in an animation of visible channel images (below). The oblique viewing angle from this satellite helped to emphasize the large vertical extent of the eruption cloud.

GOES-13 visible channel images

An animation of Meteosat-9 SEVIRI volcanic ash retrieval product 4-panel images (below) indicated that the initial volcanic cloud was ice-dominated (darker red color enhancement on the false color Red/Green/Blue or RGB images in the upper left panel). Around 22:00 UTC, the signal of an SO2 cloud (green color enhancement) began to appear around the northern and northeastern edges of the eruption cloud — very high values of SO2 were subsequently seen moving northward, using data from the OMI instrument.

A more distinct volcanic ash signal (pink color enhancement on the RGB image) became obvious as time progressed along the southern and southeastern edges of the eruption cloud, and by 06:00 UTC on 22 May the retrieved maximum ash height had reached 7.52 km (with the mean volcanic ash particle effective radius at 11.14 Âµm). Total volcanic ash mass loading had increased to 44.97 kilotons by 06:00 UTC.

Meteosat-9 volcanic ash retrieval 4-panel images

CIMSS participation in GOES-R Proving Ground activities includes the generation of these SEVIRI volcanic ash retrievals, which offers a demonstration of the type of products that will be available for volcanic ash monitoring with the ABI instrument on the future GOES-R satellite.

===== 22 MAY UPDATE =====

Meteosat-9 visible channel images (below; click image to play animation) showed that multiple volcanic eruption clouds were still reaching significant vertical heights, with much of this high-altitude material drifting northward. Another lower-altitude hazy volcanic ash cloud could also be seen spreading out just off the southern coast of Iceland. See the US Air Quality blog for MODIS true color images and OMI SO2 images of the volcanic eruption.

McIDAS images of GOES-13 0.63 Âµm visible channel data (above) revealed a hazy plume moving southward along the Pacific Northwest coast of the US late in the day on 18 May 2011. The airborne smoke showed up very well due to the favorable “forward scattering angle” during the later hours of the early evening, as viewed from the GOES-13 (GOES East) satellite located at 75Âº West longitude.

It is very likely that this hazy plume was due to long range transport of smoke from recent fire activity in northern Alberta, Canada — large smoke plumes were seen over that region on GOES-11 and GOES-13 visible channel images as early as 15 May. NOAA ARL HYSPLIT model backward trajectories initialized at altitudes of 6 km, 7 km, and 8km (below) did indeed indicate transport from the region of the fires. Lidar data from the University of British Columbia showed that the portion of the aerosol layer over Vancouver was located at altitudes of 7-8 km.

NOAA ARL HYSPLIT model backward trajectories

AWIPS images of GOES-11 6.7 Âµm “water vapor channel” imagery with overlays of MADIS hourly atmospheric motion vectors or “satellite winds” (below) showed that there was a cyclonic circulation aloft around a small vortex located over British Columbia, Canada.

GOES-11 water vapor images + MADIS hourly atmospheric motion vectors

On the following morning of 19 May, a favorable forward scattering angle early in the day allowed the long smoke plume to be seen on AWIPS images of GOES-11 0.65 Âµm visible channel data (below; click image to play animation) — the leading edge of the smoke plume appeared to have reached southern California by that time. The AWIPS images are a composite of GOES-11 (GOES-West) and GOES-13 (GOES-East) visible channel data; the vertical “seam” between the 2 satellite sources should be fairly easy to see.